The field of the invention pertains to spark ignition internal combustion engines, and in particular, to engines that use a throttling plate and passive valves in the inlet flow circuit to each cylinder. Such throttling plates and passive valves cause throttling losses that reduce engine thermodynamic efficiency, especially under part load conditions.
Examples of modern reed valve assemblies for diesel engines are disclosed in U.S. Pat. No. 4,970,996 and for high performance spark ignition engines in U.S. Pat. No. 4,879,976. In both disclosures the reeds are positioned on wedge shaped supports located in the inlet passage to the cylinder. The reeds open passively in response to a relative vacuum downstream of the reeds.
U.S. Pat. No. 4,901,682 illustrates another form of reed valve wherein the valve body is formed of insulating material. U.S. Pat. No. 4,158,352 discloses a small flapper valve mounted on a throttle plate. The flapper valve operates to assist in air intake during the initial cranking phase of engine start-up.
The above examples all illustrate passively operated reed valves, however, actively operated throttle valves of various forms are known. U.S. Pat. No. 4,363,302 discloses a cam operated flat slotted slide valve. The fixed slots are formed by a plurality of air foils mounted in the intake passage. A flat slotted plate is reciprocally driven by the cam,
U.S. Pat. No. 4,940,031 discloses a solenoid employed to set the idle opening position of a throttle plate in either of two slightly open throttle plate settings. U.S. Pat. No. 4,875,447 discloses a solenoid controlled valve in a passage communicating between the upstream and downstream sides of a pair of throttle plates. To control the amount of suction air, an electronic control unit operates the solenoid in response to various engine operating conditions. And U.S. Pat. No. 4,760,825 discloses a throttle plate rotated by an electronic control unit in response to various engine operating conditions. The device includes an air flow meter in the inlet passage.